Substituted cycloalkanediones

ABSTRACT

Novel substituted cycloalkanediones and their use for the control of weeds.

This invention relates to substituted cycloalkanediones and the use ofthese compounds for the control of weeds.

More particularly, the compounds of the present invention arerepresented by the following formula (A): ##STR1## wherein, n is zero,one, two or three;

R is ##STR2## R¹ is hydrogen or lower alkyl; W is oxygen, sulfur oramino;

Q is oxygen, sulfur or amino;

each of Y and Z is independently selected from hydrogen, lower alkyl,lower haloalkyl, lower alkoxy, lower haloalkoxy, halogen, nitro andcyano; and

Each of X' and X" is independently selected from hydrogen, lowerhaloalkyl, lower alkoxy, halogen and nitro, provided that both X' and X"cannot be trifluoromethyl, methoxy or nitro.

In the description and claims hereinafter, each of R, R¹, Q, W, X', X",and Y is as defined above, unless otherwise specified.

Compounds of the present invention of formula (A) can be synthesized byreacting an acid halide (I) (XX is Br, Cl or F) with an metal salt of acycloalkanedione (II) in a non-polar organic solvent such as ether ortetrahydrofuran. The metal is preferrably chosen from lithium, thalliumor magnesium. When the thallium salt is used, the halo atom (XX) shouldbe fluoro. ##STR3##

Alternatively, the compounds of formula (A) can be prepared by reactingtogether a carboxylic acid (III) and a cycloalkanedione (IV) in thepresence of diethyl phosphorocyanidate and a base such as triethylamineor potassium carbonate. ##STR4##

The following terms, wherever used in the description herein and in theappended claims, have the meaning defined below, unless otherwisespecified hereinafter.

The term "lower alkyl" refers to an alkyl group, straight or branched,having a chain length of one to eight carbon atoms. The term "lowerhaloalkyl" refers to a lower alkyl group substituted with one to threehalogen atoms.

The term "lower alkoxy" refers to an alkoxy group, straight or branched,having a chain length of one to eight carbon atoms. The term "lowerhaloalkoxy" refers to a lower alkoxy group substituted with one to threehalogen atoms.

The compounds of the present invention have one or more asymmetriccarbon atoms. The present invention includes each of the opticallyactive isomers and racemic mixtures thereof. In the exampleshereinafter, unless otherwise specified, the compound prepared is aracemic mixture.

The novel compounds of formula (A) are useful for the control of weeds,using pre- and/or post-emergent treatments. The compound can be appliedin the form of dusts, granules, solutions, emulsions, wettable powders,flowables and suspensions. Application of a compound of the presentinvention is made according to conventional procedure to the weeds ortheir locus using an herbicidally effective amount of the compounds,usually from about one-half or less to ten pounds per acre.

While some of the compounds of the present invention have activity onbroad leaf plants, the compounds, in general, demonstrate a higher levelof herbicidal activity on the grass weeds. Grass plant (weed) species onwhich the compounds of the present invention show effective herbicidalactivity include shattercane, crabgrass, sprangletop, wild oats,bermudagrass, tall fescue, rice, wheat, barley, corn, blue panicum,foxtails, rough bluegrass, winter rye, annual ryegrass, watergrass andJohnsongrass. It appears to be most effective to apply the activecompound prior to the heading stage of the grass weed.

Methods of preparing herbicidal formulations which can be used with acompound of the present invention are described in the literature alongwith suitable liquid and solid carriers, such as in U.S. Pat. Nos.4,192,669 and 4,163,661, which are incorporated herein by reference. Theoptimum usage of a compound of the present invention is readilydeterminable by one of ordinary skill in the art using routine testingsuch as greenhouse testing and small plot testing.

The compounds of the present invention, in view of their broadspectrumgrass weed herbicidal activity, can be advantageously combined withbroadleaf weed herbicides for broadspectrum postemergence weed controlin most broadleaf crops. Examples of herbicides which can be combinedwith a compound of the present invention include glyphosate, bentazone,diuron, paraquat, 2,4-D, 2,4-DB, diquat, endothal, dinoseb, dicamba,norflurazon, nitrofen, cyanozine, methazole, mefluidide, metribuzin,cycloate, fluometuron, linuron, dalapon, bifenox, and alachlor forcontrolling a broad spectrum of weeds.

The term "herbicide," as used herein, refers to an active ingredientwhich modifies the growth of plants because of phytotoxic or plantgrowth regulating properties so as to retard the growth of the plant ordamage the plant sufficiently to kill it.

The following examples are provided to illustrate the practice of thepresent invention. Temperature is given in degrees Centigrade. "RT"means room temperature.

EXAMPLE 1

Ethyl bromide (6 g, 55 mmol) is added to magnesium turnings (1.34 g) inthe presence of tetrahydrofuran (THF; 15 ml). After reaction iscomplete, the solution is diluted to 50 ml with THF cooled in an icebath and cyclopentane-1,3-dione (50 mmol) is added rapidly withstirring. THF (250 ml) is added to this mixture and it is allowed towarm to RT. 2-[4-(4-Trifluoromethylphenoxy)phenoxy]propionic acidchloride (55 mmol) is added dropwise with stirring, and the mixture isallowed to stand at RT for 30 minutes. It is then poured into a mixtureof ice, water and ether. The aqueous layer is extracted several timeswith ether. The combined ether extracts are washed with water, driedover sodium sulfate and the solvent is removed to give2-[[2-[4-(4-trifluoromethylphenoxy)phenoxy]propionyl]]cyclopentane-1,3-dione(V; Y is H, Z is CF₃, R¹ is CH₃ and n is one). ##STR5##

EXAMPLE 2

Following the procedure of Example 1, the magnesium salt ofcyclopentane-1,3-dione is reacted with each of2-[4-(2-chloro-4-trifluoromethylphenoxy)phenoxy]propionic acid chloride,(2-[4-(2,4-diclorophenoxy)phenoxy]propionic acid chloride and2-[4-(2-nitro-4-trifluoromethylphenoxy)phenoxy]propionic acid chlorideto yield, respectively,

2-[[2-[4-(2-chloro-4-trifluoromethylphenoxy)phenoxy]propionyl]]cyclopentane-1,3-dione(V; Y is Cl, Z is CF₃, R¹ is CH₃ and n is one),

2-[[2-[4-(2,4-dichlorophenoxy)phenoxy)propionyl]]cyclopentane-1,3-dione(V; each of Y and Z is chloro, R¹ is CH₃ and n is one), &

2-[[2-[4-(2-nitro-4-trifluoromethoxyphenoxy)phenoxy]propionyl]]cyclopentane-1,3-dione(V; Y is NO₂, Z is CF₃, R¹ is CH₃ and n is one).

EXAMPLE 3

To THF (250 ml) under N₂ with stirring is added cyclopentane-1,3-dione(0.10 mol) and 2,2'-bipyridyl (˜3-5 mg) as an indicator. After coolingto -70°, n-butyllithium in hexane is added slowly while the temperatureis allowed to rise to -5° near the end of the addition (˜130 ml of 1.6 Msolution, 0.20 mol). After the pink indicator persists at -5°, themixture is recooled to -65° and4-(4-trifluoromethylphenoxy)phenoxyacetyl chloride is added dropwiseover 5 min. After 1 hour, the reaction mixture is diluted with water andether is added. The organic layer is washed with water, dried oversodium sulfate and concentrated in vacuo to give2-[4-(4-trifluoromethylphenoxy)phenoxyacetyl]cyclopentane-1,3-dione (V;Y is H, Z is CF₃, R¹ is H and n is one).

EXAMPLE 4

2-[4-(4-Trifluoromethylphenoxy)phenoxy]propionic acid fluoride (0.10mol) is added to a solution of the thallium salt ofcyclohexane-1,3-dione in ether (200 ml) over a period of 30 minutes. Themixture is filtered and the filtrate is concentrated to give2-[[2-[4-(4-trifluoromethylphenoxy)phenoxy]propionyl]]cyclohexane-1,3-dione(V; Y is H, Z is CF₃, R¹ is CH₃ and n is two).

In the same manner, 2-[4-(4-trifluoromethylphenoxy)phenoxy]propionicacid fluoride is reacted with the thallium salt of cyclobutane-1,3-dioneto yield2-[[2-[4-(4-trifluoromethylphenoxy)phenoxy]propionyl]]cyclobutane-1,3-dione(V; Y is H, Z is CF₃, R¹ is CH₃ and n is zero).

The thallium salts of cyclohexane-1,3-dione and of cyclobutane-1,3-dionecan be prepared as described by J. M. McIntosh et al., Can. J. Chem.51:843 at 846 (1973), the disclosure of which is incorporated herein byreference.

EXAMPLE 5

Following the procedure of Example 3, the lithium salt ofcyclopentane-1,3-dione is reacted with each of the acid chlorides undercolumn I to give the corresponding cyclopentanedione under column II.

I

1. 2-[4-(3-chloro-5-trifluoromethyl-2-pyridyloxy)phenoxy]propionic acidchloride

2. 2-[4-(5-trifluoromethyl-2-pyridyloxy)phenoxy]propionic acid chloride

3. 2-[4-(6-fluoro-2-quinolyloxy)phenoxy]propionic acid chloride

4. 2-[4-(6-chloro-2-quinoxalinyloxy)phenoxy]propionic acid chloride

5. 2-[4-(benzo-1,3-oxazolyl-2-oxy)phenoxy]propionic acid chloride

II

1.2-[[-2-[4-(3-chloro-5-trifluoromethyl-2-pyridyloxy)phenoxy]propionyl]]cyclopentane-1,3-dione

2.2-[[2-[4-(5-trifluoromethyl-2-pyridyloxy)phenoxy]propionyl]]cyclopentane-1,3-dione

3.2-[[2-[4-(6-fluoro-2-quinolyloxy)phenoxy]propionyl]]cyclopentane-1,3-dione

4.2-[[-2-[4-(6-chloro-2-quinoxalinyloxy)phenoxy]propionyl]]cyclopentane-1,3-dione

5.2-[[2-[4-(benzo-1,3-oxazolyl-2-oxy)phenoxy]propionyl]]cyclopentane-1,3-dione

What is claimed is:
 1. A compound of the following formula (A): ##STR6##wherein, n is zero, one, two or three;R is ##STR7## R¹ is hydrogen orlower alkyl; W is oxygen, sulfur or amino; and each of Y and Z isindependently selected from hydrogen, lower haloalkyl and halogen.
 2. Acompound according to claim 1 wherein Y is hydrogen and Z istrifluoromethyl.
 3. A compound of the following formula, according toclaim 1: ##STR8##
 4. A compound according to claim 3 wherein W isoxygen, R¹ is methyl, n is one or two, Y is hydrogen chloro and Z ischloro or trifluoromethyl.
 5. A compound according to claim 4 wherein Yis chloro and Z is trifluoromethyl.